Combine harvesters are used in agriculture to harvest core-containing fruit, such as wheat or corn, from a field. During the harvesting operation, the plants are cut off or gathered. By means of a threshing device and a separation device, the grains are separated from the remaining harvested crop residues (in particular straw). A cleaning device then separates the grains from smaller harvested crop residues, such as straw fragments and chaff. Finally, the grains are placed in intermediate storage in a grain tank and transferred to a transport vehicle.
In a combine harvester, various operating parameters have to be specified by the operator, such as the rate of advance, the settings of the threshing device (rpm, threshing gap), and settings of the cleaning device (blower rpm, sieve opening size). The rate of advance defines the harvested crop throughput through the combine harvester, which, on the one hand, should not be excessively small in order to use the capacity of the combine harvester as well as possible, and, on the other hand, it should however also not be excessively large, because then the losses (which as a rule depend exponentially on the throughput), i.e., the quantity of grains released onto the field with the harvested material residue by the combine harvester at the rear side increase excessively. For the setting of the rate of advance, the operator usually uses grain loss sensors that are arranged for the detection of the lost grains downstream of the cleaning device and of the separation device. Such grain loss sensors as a rule comprise impact plates, on which oscillations are generated at the time of the impact of the loss grains, which are detected by an oscillation sensor and are verified by means of an electronic verification system and used by the operator for controlling a display device. For this purpose, reference is made to the disclosure of DE 40 35 470 C2.
The usual grain loss sensors, however, have the disadvantage that they have to be calibrated regularly in order to be able to display sufficiently precise values, because the lost grains generate different oscillations of the impact plates under different environmental conditions, such as, temperature and humidity. In addition, only a small proportion of the lost grains in fact reaches the grain loss sensors. The remaining lost grains are embedded in the straw or chaff. If the harvest conditions change, the proportion of grains that reach the grain loss sensor changes. Thus, the generated oscillations also depend on the harvest crop type and also on the respective throughput.
Thus, in the prior art, the operator of the combine harvester performs the following steps in order to calibrate the grain loss sensors: He moves the combine harvester at a certain constant speed over the field, until the processing procedure within the combine harvester has stabilized. Then, the loss value displayed on the display device is recorded or stored, and a test tray (see patent publications DE10062114 C2 and EP 1736044 A1) is released, after which the combine harvester is stopped, and the driver descends from his/her workplace in order to count the grains contained in the test tray. In many cases, this process occurs also without [a] test tray, and the operator counts the grains lying within a certain area of the ground. The number of lost grains is then entered into a separate computer in order to determine the losses as percentages relative to the throughput, or in order to read said percentages from a table on the basis of the counted lost grains. These relative losses are then used for the calibration of the grain loss sensor. As a rule, this procedure has to be carried out repeatedly until a speed has been found at which a reasonable compromise between throughput performance and acceptable losses is obtained. Finally, the combine harvester is moved manually or automatically at a speed corresponding to the determined loss value (or the throughput associated with said value, see EP 1243173 A1), so that, in the case of dense crops, the speed of advance can be slower and faster in the case of non-dense crops.
Similar processes also have to be carried out for the threshing assembly settings and the cleaning settings, for which automation has already been proposed (EP 1297733 A1, EP 1371278 A2), wherein the operator enters his/her estimate of the process result at different operating parameters into an on-board computer and on the basis of this, an automatic optimization of the process occurs.
The above-described calibration process for the grain loss sensors has to be repeated several times daily, which turns out to be quite time consuming and therefore, in numerous cases, the process is carried out only rarely or not at all. Thus, the combine harvester does not always work with optimal operating parameters, resulting either in high losses or in its capacity not being used optimally.
The problem that is the basis of the invention involves indicating a procedure that is improved compared to the prior art, for optimizing an operating parameter of a combine harvester, and a corresponding arrangement.